Dissertation
Dissertation > Medicine, health > Basic Medical > Medical science in general > Biomedical Engineering > General issues

The Reliability of Tooth Image Reconstruction from CT Scans and Impression

Author SunLi
Tutor ChuBingFeng;LiHongBo
School PLA Postgraduate Medical School
Course Geriatric Dentistry
Keywords 3D scanner Three-dimensional reconstruction Dental morphology CT scan Dental impression material
CLC R318.0
Type Master's thesis
Year 2010
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3D medical image reconstruction is the basis for the implementation of computer-aided analysis and treatment design. In recent years, with spiral CT, cone-beam CT, the rapid development of Micro-CT technology, according to the CT scan data to establish a three-dimensional digital model has become a CAD / CAM, body motion simulation, and biomechanics research method. Due to the complex structure of the teeth and oral and maxillofacial bone tissue and teeth, small size, irregular in shape, edentulous three-dimensional digital model reconstruction based on CT scan data difficult and prone to large errors, the accuracy of three-dimensional digital model directly affects the CAD / CAM, motion analysis and biomechanical analysis of the results. This topic to extracted teeth, monkey dentition, for example, the use of the image to fit the volume rate of change of the error distribution range of statistics, and rebuild the model analysis, the preliminary study on the tooth surface morphology of the three-dimensional reconstruction based on CT scan data accuracy. Experiment: OKIO-V-100 three-dimensional optical scanning system accuracy testing purposes: evaluation OKIO-the V-100 three-dimensional optical scanning system accuracy. Methods: standard, the use OKIO-V-100 three-dimensional optical scanning system scan standard mold five standard ball with China Institute of Metrology detection, access to the center of the sphere distance, to calculate the measurement error. The results: Ball 1 - ball 2 the center of the sphere from the standard spherical center distance error as 0.0034 ± 0.0016mm; ball 2 - ball 3 the center of the sphere from the standard spherical center distance error of 0.0064 ± 0.0048mm. Conclusion: OKIO-V-100 three-dimensional optical scanning system accuracy to meet the requirements of this study. Experiment II: the reconstruction of the CT scan data away from the purpose of the three-dimensional precision study of the surface morphology of the extracted teeth: three-dimensional evaluation based on spiral CT, cone-beam CT, Micro CT scan data reconstruction accuracy of the morphology of the surface of the teeth. Method: full 18 isolated teeth (anterior teeth, premolars, molars of 6), respectively, with spiral CT, cone-beam CT, Micro CT OKIO-V-100 3D optical scanning system scan using Mimics software dental digital model reconstruction and Geomagic qualify 9.0 software, digital model as the standard model OKIO-V-100 reconstruction of three-dimensional optical scanning system. Respectively three CT scan reconstruction of the digital model and the standard model image fitting in fitting the image using the different sizes of the different color marker error value, and generating an error histogram. Calculated based on the difference between the volume of the digital model with the standard model of teeth of different CT scan image reconstruction to arrive at the volume ratio of the volume difference between the standard model (the rate of change in volume RVD / VS), paired t-test and analysis of variance methods, analysis different types of CT scanners, different tooth position of the RVD / VS. Results: Compared with the standard model, using Micro CT, cone-beam CT, spiral CT scan image reconstruction teeth digital model RVD / VS were 5.11 ± 2.58%, 20.73 ± 4.61%, 24.60 ± 6.52%, different CT scan The difference was statistically significant (P lt; 0.01) between the instrument. Between the different types of isolated teeth RVD / VS significant difference (P lt; 0.01). Conclusion: compared with spiral CT, cone-beam CT, the dental digital model of the Micro CT scan image reconstruction, and the standard model have different levels of zoom, enlarge different parts in different teeth and teeth is inconsistent. Experiment III: the purpose of comparison of the accuracy of obtaining the model of the three-dimensional three impression material: dimensional evaluation alginates, condensation silicone rubber, polyether precision of the impression of the three rubber-based dental impression material. Method as a standard model: the monkey on the mandibular teeth, three impression materials preparation 5 to pay the plaster model OKIO-V-100 three-dimensional optical scanning system scan standard model and a plaster model, and extract the scanned image of the plaster model the dentition image with the standard model images to fit, get set the dentition-section body volume and the obtained data were analyzed by ANOVA and rank sum test statistical analysis, to observe the different impression materials taken between the impression and the standard model three-dimensional form of the deviation of the distribution law. Results: standard model scanned image comparison, the use of alginates, and the condensation silicone rubber, polyether rubber-like three impression material prepared stamper clone plaster model of the scanned image after dentition sectional average volume change rate (RVD / VS) were -5.84%, -3.21%, -0.63%, the alginate group with condensation silicon rubber, polyether rubber group cross-section volume difference was statistically significant (P lt; 0.05); poly ether rubber group closest to the standard model; condensation silicon rubber and alginate group, a polyether group (P gt; 0.05), condensation silicone rubber group (P gt; 0.05), jaw RVD / VS no statistical difference ; alginate group, a statistically significant difference (P lt; 0.05). The maximum deviation of the fitting image appear in the the tooth neck with gum tissue contact site. Conclusion: The three impression materials, plaster casts and the standard model compared to the volume are smaller, polyether rubber impression materials modulo accuracy is superior to the condensation silicone rubber, condensation silicone rubber is superior to alginate class impression materials, dental neck and gum tissue contact areas modulo errors. Experiment: preliminary study of the accuracy of digital model based on CT scan data and an impression of three-dimensional reconstruction of the dentition purpose: To evaluate the CT scan data and dentition impression reconstruction of the dentition digital model accuracy. Monkey dentition specimens: OKIO-V-100 three-dimensional optical scanning system scan to obtain the standard model; spiral CT, cone-beam CT scan data reconstruction of mandibular dentition three-dimensional digital model; preparation monkey dentition specimens impression irrigation system plaster model OKIO-V-100 three-dimensional optical scanning system scan reconstruction dentition morphology. Respectively, a digital image of the CT scan reconstruction, plaster model scan reconstruction image and the standard model dentition image fitting. Fitting different colors used in the image markers different the size of the error value, and generating an error histogram. Fitting image to simulate plane intercept dentition morphology, analysis of the difference between the model with the volume of the standard model of the dentition digital intercepted by the different position of the plane and RVD / VS. RVD / VS Results: according spiral CT, cone-beam CT scan data reconstruction dentition three-dimensional digital model up to over 40%, with the analog plane gingival smaller trend to mobile, RVD / VS; plaster model scan reconstruction the model with simulated plane gingival larger trend to mobile, RVD / VS. Conclusion: According to the helical CT, cone-beam CT images reconstructed dentition digital model, compared with the standard model has a greater degree of amplification; the degree of deformation of the different positions of the plane of the interception dentition image is inconsistent, CT scans, and impression combine the reconstruction of 3D models may be a method to obtain high precision three-dimensional the edentulous digital model.

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